Brijesh Kumar Singh

In vivo evaluation of chitosan–PVP–titanium dioxide nanocomposite as wound dressing material

In our present study, the blends of chitosan, poly(N-vinylpyrrolidone) (PVP) and titanium dioxide (TiO2) were investigated by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The size distribution of the TiO2 nanoparticles was measured using transmission electron microscope and scanning electron microscope. The studies on the mechanical properties of composite material indicate that the addition of TiO2 nanoparticles increases its strength. The prepared nanocomposite dressing has excellent antimicrobial efficacy and good biocompatibility against NIH3T3 and L929 fibroblast cells. Compared to conventional gauze, soframycin skin ointment and chitosan treated groups, the prepared nano dressing caused an accelerated healing of open excision type wounds in albino rat model. The synergistic effects of nanocomposite dressing material like good antibacterial ability, high swelling properties, high WVTR, excellent hydrophilic nature, biocompatibility, wound appearance and wound closure rate through in vivo test makes it a suitable candidate for wound healing applications.

Chitosan-PVP-nano silver oxide wound dressing: in vitro and in vivo evaluation.

The main aim of this work was to prepare wound healing material with chitosan, poly vinyl pyrrolidone (PVP), silver oxide nanoparticles. The prepared chitosan, chitosan-PVP-nano silver oxide (CPS) films were characterized for their thermal behaviour, morphological properties, mechanical properties, antibacterial properties and wound healing properties. The CPS film found higher antibacterial activity because the materials both chitosan as well as silver oxide poses good antibacterial activity. L929 cell lines were for cytotoxicity study and Adult male albino rats (140-180 g) were used for wound healing study. The prepared film has more wound healing property than of cotton gauge, 100% chitosan and other reported chitosan based dressings.

Chitosan silk-based three-dimensional scaffolds containing gentamicin-encapsulated calcium alginate beads for drug administration and blood compatibility

In the present study gentamicin was encapsulated within calcium alginate beads and incorporated into porous chitosan, gelatin, double-hybrid silk fibroin, chitosan/gelatin and double-hybrid silk fibroin/chitosan scaffolds. Physiochemical, morphological and biological properties of fabricated amenable model systems were evaluated, revealing hemocompatible nature of double-hybrid silk fibroin/chitosan and double-hybrid silk fibroin scaffolds of hemolysis %<5 and porosity >85%. Fourier transform infrared results confirmed the blend formation and scanning electron microscope images showed good interconnectivity. Double-hybrid silk fibroin/chitosan-blended scaffold shows higher compressive strength and compressive modulus than other fabricated scaffolds. A comparative drug release profile of fabricated scaffolds revealed that double-hybrid silk fibroin/chitosan scaffold is a pertinent model system because of its prolonged drug release, optimal hemocompatability and high compressive modulus.

Self-assembling N-(9-Fluorenylmethoxycarbonyl)-l-Phenylalanine hydrogel as novel drug carrier.

Supramolecular hydrogel as a novel drug carrier was prepared from N-(9-Fluorenylmethoxycarbonyl) (Fmoc) modified l-phenylalanine. Its different properties like stability at different pH, temperature and rheology were evaluated in reference to salicylic acid (SA) as a model drug, entrapped in the supramolecular hydrogel network. The release behaviour of SA drug in supramolecular hydrogel was investigated by UV-vis spectroscopy. The influence of hydrogelator, pH values of the accepting media, temperature and concentration of SA drug on the release behaviour was investigated under static conditions. The results indicated that the release rate of SA in the supramolecular hydrogels was slightly retarded with an increase of the hydrogelator concentration. Also, the release rates of SA increased with an increase of temperature and its concentration. Furthermore, the release behaviour of SA was found to be different at various pH values in buffers. The study of the release kinetics indicated that the release behaviour of SA from the carrier was in accord with the Peppas model and the diffusion controlled mechanism involved in the Fickian model.

Colorimetric and ON–OFF–ON fluorescent chemosensor for the sequential detection of Cu(II) and cysteine and its application in imaging of living cells

An easy-to-prepare colorimetric and ON–OFF–ON fluorescent naphthol derivative 1 has been synthesized and characterized for sequential detection of Cu2+ and cysteine. Chemosensor 1 detects Cu2+ selectively in DMSO/H2O (3 : 7 v/v) by changing its UV-visible spectrum and color (colorless to yellow), leading to the formation of 1-Cu(II) complex. The resultant 1-Cu(II) complex recognizes cysteine (Cys) and the solution turns colorless with regeneration of the absorption band of 1. The detection limit of 1 for Cu2+ ion is found to be 0.27 μM, which is much lower than that recommended by WHO for drinking water (30 μM). Cu2+ ion exhibits quenching of the fluorescence intensity of 1, which is restored upon the addition of cysteine. Chemosensor 1 is used as an imaging reagent for detection of the cellular uptake of Cu2+ ion in A549 cell line (human lung carcinoma cell).

Chitin, Chitosan, and Silk Fibroin Electrospun Nanofibrous Scaffolds: A Prospective Approach for Regenerative Medicine

Intensive studies have been done to a wide range of natural and synthetic polymeric scaffolds which have been done for the use of implantable and temporal devices in tissue engineering. Biodegradable and biocompatible scaffolds having a highly open porous structure with compatible mechanical strength are needed to provide an optimal microenvironment for cell proliferation, migration, differentiation, and guidance for cellular in growth at host tissue. One of the most abundantly available biopolymer chitins and its deacetylated derivatives is chitosan which is non-toxic and biodegradable. It has potential biomedical applications such as tissue engineering scaffolds, wound dressings, separation membranes, antibacterial coatings, stent coatings, and biosensors. Recent literature shows the use of chitin and chitosan in electrospinning to produce scaffolds with improved cytocompatibility, which could mimic the native extra-cellular matrix (ECM). Similarly, silk from the Bombyx mori silkworm, a protein-based natural fiber, having superior machinability, biocompatibility, biodegradation, and bioresorbability, has evolved as an important candidate for biomedical porous material. This chapter focuses on recent advancements made in chitin, chitosan, and silk fibroin-based electrospun nanofibrous scaffolds, emphasizing on tissue engineering for regenerative medicine.

Optical and Electrical Characterization of Stable p-Type ZnO Thin Films Obtained by Bismuth Doping

We report the growth of stable p-type ZnO thin films obtained by doping bismuth (Bi) in ZnO and deposited over ITO coated glass substrate. The Bi doped ZnO thin films have been deposited by a sol-gel spin coating method using zinc acetate and bismuth nitrate as main precursors. The structural, optical and electrical properties of annealed Bi doped thin films have been studied in detail using X-ray diffraction (XRD), Atomic force microscopy (AFM), ellipsometry, hot probe system and Hall measurement. The presence of strong diffraction peak along (101) obtained from the XRD spectra shows that the high-quality Bi doped ZnO nanostructures grow along (101) orientation. A number of important micro-structural parameters for the thin films such as grain size, lattice parameters, stress and texture coefficient have been calculated, in order to show the effect of Bi incorporation in ZnO thin film. Further, transmittance has been calculated over the range of 350- 800 nm wavelength regions. The optical band gap of Bi doped ZnO films have also been calculated for different concentrations of Bi using the data taken by an ellipsometer. Hot probe characterization method has been used to ascertain the type of semiconductor thin film and it was observed that films doped with the concentration of 10 mol% Bi show p-type nature that was found to be stable over the period of eight months. Further, in order to calculate the resistivity, hole concentration, and mobility of p-type Bi doped ZnO thin film Hall measurement have been performed.

Fabrication and characterization of thin-film heterojunction diodes for smart systems

In the present article we report copper (Cu) doped ZnO (p-type) thin-film based heterojunction diodes grown on p/n-Si substrate. Sol-gel spin coating method has been used to deposit the Cu doped ZnO thin films on p/n-type silicon. The p-type nature of the deposited Cu doped ZnO thin films have been confirmed by hot point probe method. The electrical parameters of the as fabricated devices have been gauged from I-V characteristics. The ZnO based devices on Si platform are expected to be deployed in future generation smart systems for UV/gas sensing and photovoltaic applications.

Short channel effects (SCEs) characterization of underlaped dual-K spacer in dual-metal gate FinFET device

FinFETs are new structures for scaling the devices at sub-nanometer regime to continue the Moores law. To increase the performance of FinFETs, a dual metal gate with underlap concepts has been introduced. Moreover, its performance can be enhanced by spacers. The dual metal gate comprises of two different workfunction materials (Molybdenum and Tungsten) for double gate (DG) and triple gate (TG) FinFET structures with different underlap length (LUN) has been presented. The TG FinFET exhibits the better control of short channel effects (SCEs) over the DG FinFET device. The significance of the spacer with a variation of spacer length poses the use of dual-k spacer in TG FinFET device to procure the better performance such as high on-current (Ion), Ion/Ioff ratio and smaller subthreshold swing (SS), drain induced barrier lowering (DIBL). The simulation carried by SILVACO ATLAS, and it shows that TG FinFET with different combination of dual-k (smaller high-k length (Lhk), larger low-k length (Llk)) draws an attention for nanoscale application.

Determination of optical parameters of p-ZnO thin film obtained by Bi doping

In the present paper, we have investigated the optical property of p-ZnO thin films obtained by bismuth doping. Bi doped p- type ZnO film was grown on ITO coated glass substrate using sol-gel technique. Hot point probe method has been used to analyze the nature of semiconductor thin film and it was observed that film doped with the concentration of 10 mol % Bi shows P-type nature. The XRD spectra of thin films shows that a high quality Bi doped ZnO nanostructures grows along (101) plane. The optical parameters of the thin film like dielectric constant, extinction coefficient and refractive index have been calculated over the range of 300-800 nm wavelength region.